There are a large number of different types of heat sensing devices utilized in fire detection systems presently on the market. One which is specially used in commercial and industrial applications, particularly in commercial airliners, is tubular in configuration and may extend several hundred feet. One such device manufactured by Systron-Donner Corporation, assignee of the present invention, is referred to as a continuous length pneumatic detector. This particular heat sensing device carries helium gas throughout its entire tubular length and operates by monitoring the internal pressure of this gas as the latter expands in response to elevated temperatures.
From the foregoing, it should be apparent that tubular heat sensing devices of the type described are particularly suitable for protecting large areas, particularly engine and ducting areas typically found in commercial airliners. For example, as many as 24 or more individual heat sensing devices which all together extend over more than 300 feet are presently used in a Boeing 747 type airplane. Heretofore, many of these tubular heat sensing devices have been held in place by means of spaced clamp assemblies of a particular design. This prior art clamp assembly includes a main body member adapted for connection to a given support surface and a pivotally connected secondary body member, which when interlocked with the main body, maintains a longitudinal segment of the tubular heat sensing device in place.
In order to interlock together the main body and its pivotally connected secondary body, the overall clamp assembly thus far described uses a two piece locking pin including a main shaft with an integral head at one end and a separate cross pin at the other end. This interlocking pin is fixedly connected with the secondary body member and is adapted for insertion into a cooperating through hole in the main body for rotation therein for interlocking the two body members together.
While the general way in which the clamp assembly just described functions is quite satisfactory for its intended purpose, it does have one particular drawback, specifically with respect to the design of its locking pin. As stated above, this locking pin is itself fixedly connected with the secondary body of the overall assembly and includes an enlarged head on one side of the secondary body member and a cross pin on the other side thereof. While the enlarged head is integrally formed with the shaft of the locking pin as stated, its cross pin is not. Rather, the cross pin is a separate and distinct component which is disposed (actually force fitted) through a cooperating opening extending diametrically through the otherwise free end of the shaft after the latter has itself been inserted through a cooperating opening in the secondary body member thereby interconnecting the two together. There are several disadvantages to this particular arrangement. First, the cross pin has a tendency to break off if too much torque is applied to the overall locking pin when rotating the latter in order to interlock the two body members together. Moreover, even if the pin does not break during initial installation, it has been found that vibration such as that found in an airplane can cause a cross pin to loosen to the extent that it no longer remains within the shaft of the overall locking pin. This, in turn, can cause the two interlocked bodies, that is, the main body and the secondary body of the clamp assembly to separate from one another, thereby relinquishing support of the tubular segment and exposing the latter to the possibility of damage.
As will be seen hereinafter, the present invention is directed to a clamp assembly which, in many respects, may be similar to the clamp assembly just described. However, as will be seen hereinafter, the clamp assembly constructed in accordance with the present invention includes a different locking pin, specifically one which does not have the drawbacks just discussed. The present invention is also directed to a particular way of interconnecting or interlocking the locking pin to the secondary body of the clamp assembly and to a particular hand tool for carrying this out, especially on a prior art clamp assembly which has lost its locking pin.